From: Oleg Nesterov <[email protected]>
To: Jens Axboe <[email protected]>
Cc: [email protected], [email protected]
Subject: Re: [PATCH 2/4] task_work: don't run task_work if task_work_exited is queued
Date: Tue, 7 Apr 2020 18:19:13 +0200 [thread overview]
Message-ID: <[email protected]> (raw)
In-Reply-To: <[email protected]>
On 04/07, Jens Axboe wrote:
>
> On 4/7/20 4:39 AM, Oleg Nesterov wrote:
> >
> > IIUC, this is needed for the next change which adds task_work_run() into
> > io_ring_ctx_wait_and_kill(), right?
>
> Right - so you'd rather I localize that check there instead? Can certainly
> do that.
I am still not sure we need this check at all... probably this is because
I don't understand the problem.
> > could you explain how the exiting can call io_ring_ctx_wait_and_kill()
> > after it passed exit_task_work() ?
>
> Sure, here's a trace where it happens:
but this task has not passed exit_task_work(),
> __task_work_run+0x66/0xa0
> io_ring_ctx_wait_and_kill+0x14e/0x3c0
> io_uring_release+0x1c/0x20
> __fput+0xaa/0x200
> __task_work_run+0x66/0xa0
> do_exit+0x9cf/0xb40
So task_work_run() is called recursively from exit_task_work()->task_work_run().
See my another email, this is wrong with or without this series. And that is
why I think task_work_run() hits work_exited.
Could you explain why io_ring_ctx_wait_and_kill() needs task_work_run() ?
Oleg.
next prev parent reply other threads:[~2020-04-07 16:19 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-04-06 19:48 [PATCHSET 0/4] io_uring and task_work interactions Jens Axboe
2020-04-06 19:48 ` [PATCH 1/4] task_work: add task_work_pending() helper Jens Axboe
2020-04-07 11:28 ` Oleg Nesterov
2020-04-07 15:43 ` Jens Axboe
2020-04-06 19:48 ` [PATCH 2/4] task_work: don't run task_work if task_work_exited is queued Jens Axboe
2020-04-07 11:39 ` Oleg Nesterov
2020-04-07 11:54 ` Oleg Nesterov
2020-04-07 15:40 ` Jens Axboe
2020-04-07 16:19 ` Oleg Nesterov [this message]
2020-04-07 16:59 ` Jens Axboe
2020-04-07 17:43 ` Oleg Nesterov
2020-04-07 12:47 ` Peter Zijlstra
2020-04-07 15:43 ` Jens Axboe
2020-04-06 19:48 ` [PATCH 3/4] task_work: kill current->task_works checking in callers Jens Axboe
2020-04-06 19:48 ` [PATCH 4/4] io_uring: flush task work before waiting for ring exit Jens Axboe
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